HEMI Seminar: John Borg

Dynamic Behavior of Earth Materials Subjected to Pressure-Shear Loading

Dr. John Borg, Prof. of Mechanical Engineering, Marquette University

The dynamic behavior of earth materials, such as wet and dry sand, is of interest to a variety of research fields such as defense, mining and planetary science. Plane-strain experiments are necessary to obtain the Hugoniot response of such systems however such loading is not indicative of most loading scenarios of interest.  Thus understanding oblique impact configuration (pressure-shear) can lead to a better understanding of the role of strength in the dynamic response of earth materials.  Figure 1 illustrates the basic configuration of the impact experiment and sand of interest.  A key aspect of this experiment is obtaining an accurate measurement of the normal and transverse velocity of the anvil.  For these experiments a photon Doppler velocimetry (PDV) will be used.  The configuration and the inherent difficulties of applying such a diagnostic technique to this experiment will be discussed.

Seminar will be held at 3:30 PM in Malone G33/35.

Fig. 1. (a) Oblique impact configuration with assembly with a thin sand sample with incident and reflected probes (b) Oklahoma #1 pure sand (425 – 500 μm diameter)